course, by no means incompatible with a philosophic mind; for mental characteristics have infinite capacities for permutation.  And, when both memory and philosophy combine together in one person, then indeed we have the highest sort of intellectual efficiency.  Your Walter Scotts, your Leibnitzes, your Gladstones, and your Goethes, all your folio copies of mankind, belong to this type.  Efficiency on a colossal scale would indeed seem to require it.  For, although your philosophic or systematic mind without good desultory memory may know how to work out results and recollect where in the books to find them, the time lost in the searching process handicaps the thinker, and gives to the more ready type of individual the economical advantage.

The extreme of the contrasted type, the type with associations of small persistency, is found in those who have almost no desultory memory at all.  If they are also deficient in logical and systematizing power, we call them simply feeble intellects; and no more need to be said about them here.  Their brain-matter, we may imagine, is like a fluid jelly, in which impressions may be easily made, but are soon closed over again, so that the brain reverts to its original indifferent state.

But it may occur here, just as in other gelatinous substances, that an impression will vibrate throughout the brain, and send waves into other parts of it.  In cases of this sort, although the immediate impression may fade out quickly, it does modify the cerebral mass; for the paths it makes there may remain, and become so many avenues through which the impression may be reproduced if they ever get excited again.  And its liability to reproduction will depend of course upon the variety of these paths and upon the frequency with which they are used.  Each path is in fact an associated process, the number of these associates becoming thus to a great degree a substitute for the independent tenacity of the original impression.  As I have elsewhere written:  Each of the associates is a hook to which it hangs, a means to fish it up when sunk below the surface.  Together they form a network of attachments by which it is woven into the entire tissue of our thought.  The ’secret of a good memory’ is thus the secret of forming diverse and multiple associations with every fact we care to retain.  But this forming of associations with a fact,—­what is it but thinking about the fact as much as possible?  Briefly, then, of two men with the same outward experiences, the one who thinks over his experiences most, and weaves them into the most systematic relations with each other, will be the one with the best memory.